There are various devices known in the prior art for cleaning swimming pools by crawling along their surfaces. These devices usually use power from the surface, provided by wires, or a flow of water from the surface, provided by a hose, or both. Few, if any, can clean swimming pool surfaces cordlessly and autonomously, especially in larger pools and irregularly shaped pools.
For example, Patent Publication US2014/0137343 defines a pool cleaning vehicle driven by an internal electric motor which receives power from a power cord which connects to a remote power source. The direction in which the vehicle is propelled is determined by the direction of rotation of the electric motor, which is in turn controlled by signals received from the external power supply via a floating cable. U.S. Pat. No. 8,266,752 describes automatic swimming pool cleaners which use a cleaner body traveling through a water pool in which the cleaner body is tethered to a conduit which supplies power (e.g., positive pressure water flow, negative pressure (i.e., suction) water flow, electricity, etc.) for propelling the body through the water pool. Water flow received from outside the cleaner can be coupled to a generator subsystem within the pool cleaner body, and the pressure of the water flow used to generate electric power for a controller. U.S. Pat. No. 5,985,156 defines a pool cleaner which is hydraulically powered, either by pressure or by suction, using an external hydraulic pump. Proximal and distal ends of a flexible supply hose are respectively coupled to the pump and to the pool cleaner body for producing a water supply flow through the body for powering the device. The hose is preferably configured so that it primarily lies close to the interior pool wall surface during use, with the hose being dragged along by the movement of the body through the pool.
The tethering cables required for nearly all prior submersible robotic pool cleaners, including all cleaners of comparable performance, can cause problems as the unit moves through the pool. The cables and hoses used with older units can become tangled and knotted, can become looped over obstacles inside or outside the pool, can physically obstruct the cleaning unit, and otherwise limit proper movement. Cables also limit the range of the prior art devices, and their out-of-water portions are an unsightly tripping hazard.
These problems are recognized in U.S. Pat. No. 6,299,699. It explains that in order to clean a large pool, a conventional electrical power source external to the pool is typically required. The movement and turning of the cleaner over a prolonged period of time can cause the pool cord extending to the surface to become tightly coiled and/or twisted to such an extent that it interferes with the movement of the cleaner, which can pull the cleaner off of its programmed cleaning course. To address this problem, U.S. Pat. No. 6,299,699 teaches a cleaner programmed to follow a course in which a turn in one direction that is likely to induce a right-hand twist in the power supply cord is followed by a turn in a direction that is expected to induce a left-hand twist in the cord. U.S. Pat. No. 8,266,752 similarly teaches a control subsystem for a pool cleaning robot configured to perform repositioning operations while preventing conduit tangling by avoiding excessive rotation of the body. It is simpler and more efficient, however, to program pool cleaning robots without having to worry about cords and conduits. The pool cleaner described herein avoids these conduit-related problems entirely.
If a tethered unit has its connection cut or unplugged, the unit is typically rendered inoperable with no convenient way to return it to the surface from the bottom of the pool. A user is forced to hook the unit using a long tool, or climb into the pool to retrieve the device manually.
Prior art robotic pool cleaners frequently have a problem with flipping over and getting stuck in that position, particularly if they attempt to clean the sides of pools. A user returning to check on their pool is likely to find the cleaner “belly up” at the bottom, or flipped sideways and immobile. This obviously prevents the robot from completing its task, and the user is left guessing at what point the device stopped cleaning. Typically, the user will have to right the device manually and restart the cleaning program. Thus, there is a need for autonomous pool cleaners which do not flip over, which land tracks down or wheels down when released in open water, and which can independently correct their orientation if they do settle on their back or side.
FIG. 31 in this disclosure shows a prior art apparatus 900 with known one way flap valve members 902 and 912. Valve member 902 is rotatably connected by a pivot pin 904 to a housing portion 906 and is illustrated in its closed position, while valve member 912 is rotatably connected by a pivot pin 914 to another housing portion 916 and is illustrated in its open position. In operation, water with debris pushes the valve member 912 into its open state in the direction of arrow D1 that is substantially horizontal. This occurs when a pumping system connected to apparatus 900 is operating to draw water into the system. When the pumping system is deactivated, water flow stops and a back pressure in the direction of arrow D2 moves the valve member to its closed position as illustrated by valve member 902. A problem with the prior art apparatus 900 is that debris can get caught in the joint of pivot pins 904 and 914 to prevent the valve member form closing. This in turn permits debris to empty from the filter compartment and back into the swimming pool water. Furthermore, the flow of water in the direction D1, for the open valve, can be impeded because the water has to exert force to keep the valve member 912 open, which may also be jammed closed by excess debris above the member 912. When not in a cleaning mode for the apparatus 900, water with debris applies force in the direction D2, and the flap 902 should not open and should not allow the water and/or debris to escape. However, in practice, debris may prevent the flap 902 from completely closing, leaving a partial opening where water and/or debris may escape. Flaps could also open and leak debris under force of gravity when a pool cleaning robot is tilted at an angle or vertically, such as when cleaning pool walls, especially if there is a lapse in water flow. The present invention improves on this valve arrangement.
Another shortcoming of prior art robotic pool cleaners is that they are poorly adapted to continue forward, such as by pivoting to follow a wall and/or by moving upward, when they encounter a wall or other obstacle. This is at least partially because they have all of their propulsion means—whether tracks or wheels—oriented downwards towards the ground or pool bottom. To the extent the forward-motion tracks or wheels are also exposed to the area in front of the device, in addition to the ground below, the forward-facing portion is generally at and near ground level. See, for example, U.S. Pat. No. 6,212,725 (tracks oriented down), U.S. Pat. No. 6,299,699 (tracks oriented down), U.S. Pat. No. 6,473,927 (running wheels on bottom), U.S. Pat. No. 7,849,547, (tracks oriented down), U.S. Pat. No. 8,424,142 (tracks oriented down), U.S. Pat. No. 8,800,088 (tracks oriented down), Patent Publications US 2014/0259464 (wheel assemblies at bottom corners), and US2014/0137343 (wheels at bottom corners), etc. Notably, wide spin brushes for sweeping debris generally lack sufficient motive power to lift and push a cleaning vehicle upwards. Pool cleaner vehicles which are better suited for driving directly from a horizontal pool floor up a vertical pool wall, and vice versa, are therefore desirable.
Pool cleaning vehicles which are able to at least partly climb up a pool wall, as opposed to stopping and changing direction as soon as the front of the vehicle contacts the wall, could also better clean both corner areas of pools with angular corners, and sloped areas of pools with more rounded bottom-side transition regions. This applies to both walls+floors cleaning modes, and floor-only modes where climbing just slightly up a wall can assist in cleaning the edges of a pool floor by briefly positioning water inlets on the bottom of the vehicle closer to corners.
The above designs are also not well suited for pivoting and continuing forward in the event they hit a wall at an angle, at a side or front corner of the vehicle, because they have little or no motive traction at their corners or on their left and right sides. Pool cleaning robots which are adapted to automatically pivot and continue forward on a pool floor when they intersect a wall at an angle would also provide advantages. For example, improved cleaning along the edge of pool walls by directing a vehicle which intersects a wall at an angle to conduct a pass along the edge of the wall, as opposed to stopping and pivoting in an entirely new direction. Pool robots which can push over and off of obstacles they hit at an angle will not get stuck as often, and will reach more different areas of the pool than, for example, a robot that stops and reverses or stops and pivots every time it encounters an obstacle.